You've been at the new place for two years? That's VERY different, move back tomorrow!!!

I read your original post too quickly, and thought this was a recent change and they were calling you back within a few months. Sorry, you can basically ignore what I said before (at least, in terms of being worried about trust, etc.). That guidance usually comes when people leave, and the old place realizes they needed you, make some sort of offer to get you back, and then they keep an eye out to replace you when it's convenient for them.

Two years on a resume doesn't stand out too much anymore.

As for the quality of life (including at work), those concerns still apply. We all spend way too much time at work, so it's very important to be happy there too...

Mike